Superconductivity in Metal-Rich Chalcogenide Ta2Se

Xin Gui; Karolina Górnicka; Qiang Chen; Haidong Zhou; Tomasz Klimczuk; Weiwei Xie

doi:10.1021/acs.inorgchem.9b03656

Superconductivity in Metal-Rich Chalcogenide Ta₂Se

Inorg Chem. 2020 May 4;59(9):5798-5802. doi: 10.1021/acs.inorgchem.9b03656. Epub 2020 Apr 20.

Authors

Xin Gui¹, Karolina Górnicka², Qiang Chen³, Haidong Zhou³, Tomasz Klimczuk², Weiwei Xie¹

Affiliations

¹ Department of Chemistry, Louisiana State University (LSU), Baton Rouge, Louisiana 70803, United States.
² Faculty of Applied Physics and Mathematics, Gdansk University of Technology (GUT), Narutowicza 11/12, Gdansk 80-233, Poland.
³ Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, United States.

Abstract

The metal-metal bond in metal-rich chalcogenide is known to exhibit various structures and interesting physical properties. Ta₂Se can be obtained by both arc-melting and solid-state pellet methods. Ta₂Se crystallizes a layered tetragonal structure with space group P4/nmm (No. 129; Pearson symbol tP6). Each unit cell consists of four layers of body-centered close-packing Ta atoms sandwiched between two square nets of Se atoms, forming the Se-Ta-Ta-Ta-Ta-Se networks. Herein, we present magnetic susceptibility, resistivity, and heat capacity measurements on Ta₂Se, which together indicate bulk superconductivity with T_c = 3.8(1) K. According to first-principles calculations, the d orbitals in Ta atoms dominate the Fermi level in Ta₂Se. The flat bands at the Γ point in the Brillouin zone yield the van Hove singularities in the density of states around the Fermi level, which is intensified by introducing a spin-orbit coupling effect, and thus could be critical for the superconductivity in Ta₂Se. The physical properties, especially superconductivity, are completely different from those of Ta-rich alloys or transition-metal dichalcogenide TaSe₂.